Insulating material and method of manufacturing same.



" invented certain new and useful Improvements in lowing to be a full, clear, and 'exact description of the fire-proof, electrical insulator.

i terial'has been found, so far-as I am aware, which is heat so that atteinperatures to which it may be sub- .whe're otherwise-may be used. r Porcelain is another example of an insulating material .which has a high UNITED STATES PATENT Om n- ROBERT MULLER, or MUNICH,- GERMANY.

INSULATING- MATERIAL AND'METHOD OF MANUFACTURING SAME.

Application filed January 6. 05-

To all 'whom it may concern:

- Be it known that I, ROBERT MiiLLEi' a citizen of Germany, residing at Munich, Bavaria, Germany; have Fireproof Insulating Material and Methods of Manufacturing theSame; and l'do hereby declare the folinvention, such as will; enable others skilled in the art to which it appertains to make and use the same.

This invention relates to a new fire-proof insulating material and to the method of making the same.

My new material is peculiarly adapted for use as a Many attempts have hitherto been made to produce, for electrical purposes, an insulating material which would meet all the're'quireme'nts of the art, but prior to my invention, no electrical insulating masatisfactory in all respects. p

The best insulating material, so far'as specific re sistance at normal temperatures is concerned, is rubber, but unfortunately this is affected seriously by jected in actual practice, it becomes useless. In addition to this, the cost of rubber is so great as to render its use commercially impractical in many places specific resistance; It will withstand a high degree of heat without injury to its resisting properties but, on the other hand, it also has seriousdra wba'cksj For example, it isreadily broken, cannot be'turned, bored or drilled or otherwise worked with tools, and if hard burned, a5 is necessary to produce the better class of insulation, it is relatively expensive. Moreover, its interior is yery porous so that if "the exterior enamel becomes scratched or cracked, the porcelain becomes hygroscopic to a disadvantageous extent. Wood, if dry, is also an insulator 'of relativclygood specific resistance and has the great advantage that it is readily worked with tools, b1 .1t it is very hygroscopic and burns easily. i

By my invention, I provide a fire-proof electrical insulating material which has a high specific resistance sufiiciently near to that of rubber or porcelain to make it satisfactory in the electrical art, It will withstand as high a degree of heat as it will be subjected to in practice without loss of its insulating properties, whereby it may be used in place of porcelain and it may be worked-with tools practically as easilyas wood. It takesa screw-thread very satisfactorily; Moreover, it may be also molded into shape in the same manner as rubber or porcelain and does not require the use of heat in its manufacture.

Specification of Letters Patent.

It. does not shrink as porcelain does in. molds and Patented Oct. 29, 1907. Serial No. 239.966- (Specimena) costs very much less than hard rubber or porcelain to produce.

The invention will now be described in its 'preferred embodiment when such embodiment is a solid.

In carrying out my invention, for making solid, fireproof, electricalinsulating material, I combine a fireresistant material, for example, asbestos, preferably in a coinminuted state, by means of a binder consisting of a bituminous material whose fusing point is substantially as high 'as that of mineral pitch,that is, relatively high for a binding material of this kind,

,dissolved in'a suitable volatile solvent (such as benzol or other volatile hydrocarbon, for example) of such. bituminous material, the proportions of the binder and fire-resisting material being such that a consistent plastic mass is formed which is then subjected to heavy pressure, preferably in a cold state, and dried by the evaporation of the solvent whereby a solid fire-proof and hard insulating material is obdesirable properties required in produced, the firni consisteney'of pitch after compression and evaporation of the volatile solvent makes the asbestos fibers non-hygroscopic and the solid product is in fact so non-inflammable that it may be subjected tempoiarily to an electric are without being burned up and without being softened.

In view of the fact that the bituminous material,

such for exam 1e, as mineral pitch will burn at a relafact that in the completed material produced by my lIIVGIIiIOI I, asbestos is the chief fir'e resistant material, while the pitch seems merely to impregnate and coat the particles of asbestos and to cement them -together, the amount of pitch being so minimized that the pitch in the completed material constitutes a substantially non-inflammable factor. It is possible that the ability of the pitch to resist high temperatures to which the material may be subjected without softening or igniting, is due to the fact that the relatively thin layers of the binding material-are protected by the asminimized in quantity and is present in what' may be designated as approximately filmiform layers or electrical insulating material. Moreover, owing to coatings and although made from a material which in.

ordinary relations is easily inflammable are, nevertheless, practically.non-inflammable and practically non-softing as is proven by subjection of samples to the electric arc. Herein lies a reconcilement of antagonisms, the theory of which I do not pretend to precisely understand but which I have hereinbefore set forth according to the best of mypresent understanding. By the gradual evaporation of the solvent (I recommend a volatile hydrocarbon, especially benzol, for use as a solvent), my new solid product is given a peculiar character which, although the product is refractory and hard, permits the product to be worked readily with nary Wear and tear.

In my process of making insulating material, I preferably prepare a binder consisting of 100 parts of the bituminous material, such as mineral pitch, dissolved tools and in molds without anything more than ordi at about normal temperature in approximately 20 nuted natural asbestos in .the proportion of 20 to 75 parts of the solution to 100 parts of the fire-resisting material to form a consistent plastic mass, which may be molded or otherwise compresseddnto the desired shape. The consistency of the mass will depend upon the proportions of the ingredients within the limits mentioned and may be varied according to the properties desired in the product.

Instead of using asbestos only, I may mix with it a suitable heat, water and fire-proof filler, such, for example, as quartz or kaolin; for example, 100 parts of the asbestos may be mixed with from one to 100,

parts by Weight of the filler which is preferably a finely pulverized, inorganic body. This mixture of the asbestos with the finely pulverized,,inorganic heat, wa-

ter and fire-proof filler is then combined with the binder in the same manner and in substantially the same proportions as hereinbefore described,

The volatile ingredient of the compressed product is permitted to evaporate therefrom byexposure to air whereupon the product is hardened by the evaporation of the solvent. If desired, the compressed mass may be subjected to heat for the purpose of hastening the evaporation.

The resultant product has a high degree of hardness, may be worked with facility by means of tools, takes a high polish, possesses extraordinary power of resistance to many acids and alkalies, is not hygroscopic and its resistance to heat and to the electrical current is very high. For example, it has been shown that a sample of my new product having an average thickness of 10.95 millimeters had an insulation resistance of more than live million megohms; and that when the sample of my new product was placed in an are, a black smoke was omitted. The samples became red hot and burned with a yellow flame which continued for a second or two after the sample had been removed. .After exposure to the arc, the sample had a steel blue appearance. It was consumed veryslowly, three minutes exposure slightly rounding the edges. It did not soften. By reason of these various properties, my new product is admirably adapted for employment as an the low cost of the materials employed in its manufacture and the relatively simple process required to pro duce it the insulating devices in any desired form may be made at such a-low price as to render the material capable of general use in the arts.

My new material may be used for other purposes than electrical insulation but that use is its peculiar and most striking field. If it is desired, the unpressed plastic mass above described may be used as aiircproof non-conductor in many situations where it may be allowed to harden in situ.

When the composition is compressed the voids or spaces occurring between the asbestos fibers or particles are substantially filled up, although it is probable that the evaporation of the solvent effects a certain degree of porosity in the compacted mass, the possible porosity enhancing the insulating capacity of the mass, while its exterior skin is more hardly condensed.

Having thus fully described the principle of my invention and the best mode now known to me of applying the same, what I claim as new and desire to secure by Letters Patent of the United States, is:

a pitchy substance having a relatively high fusing point.

2. An insulating material consisting of a hardened mass comprising fragments of tire resistant material ccmcnted together by a bituminous material having a relatively high fusing point, the bituminous material being only sufficient in quantity to fill substantially the voids whereby the resistant properties of the fire resistant ma' terial are made effective.

3. An insulating material comprising a hardened mass comprising asbestos fragments cemented together by a pitch having a relatively high fusing point, the pitch being only sutticient in quantity to fill substantially the voids whereby the resistant properties 01 the asbestos are made effective.

4. An insulating material consisting of a hardened mass of intimately mingled comminuted asbestos, and an inorganic heat, water and fireproof filler cemented together by a bituminous binding material having a. relatively high fusing point, the binding material being only suflicient in quantity to fill substantially the voids whereby the resistant properties of the asbestos and the inorganic liller are made effective.

5. A non-hygroscopic, fire-proof, electrical insulating composition comprising asbestos mixed with a solution of pitch and evaporatable pitch solvent, the pitch serving in the composition, after evaporation of the solvent, as a substantially tire-proof binder and also as a nomhygroscopic coating for the asbestos, the pitch also serving to (ill the voids.

U. A compressed, non-hygroscopic, fire-proof, electrical insulating composition comprising asbestos, compressed with a solution of mineral pitch and volatile hydrocarbon, the pitch serving in the compressed composition, after evaporation of the solvent, as a substantially fire-proof binder and also as a non-hygroscopic coating for the as bestos, the pitch also serving to fill the voids.

7. A compressed non-hygroscopic, Iireproof,.electrical, insulating composition comprising asbestos compressed with an evaporatable solution of mineral pitch which serves in the compressed composition, after evaporation of the volatile constituent of said solution, as a substantially fire-proof binder and also as a non-hygroscopic coating for the asbestos, the pitch also serving to till the voids.

8. A compressed non-hygroscopic, fire-proof electrical, insulating composition comprising asbestos with an evaporatablc solution of bituminous material which serves in the compressed composition, after evaporation of the cvaporatable constituent of said solution, as a substancoating for the asbestos,lthe bituminous material also serving to fill the voids.

10. The method of manufacturing insulating material which consists in dissolving a' bituminous binding material having a relatively high fusing point in a volatile solvent for such material, then incorporatin therewith a frag mental-y fire-resisting material'in sue proportions that in the completed product the binding material will only be sufiicienl: in quantity to fill completely the voids-them pressing said mass into shape and drying it.

11. The method of manufacturing insulating material which consists in dissolving a pitch having a relatively v high fusing point in a pitch solvent, incorporating therewith a fire-resistant filler, in such proportions that in the 2 5 completed product the binding material will only he sufficient to fi ll completely the voids, then molding said mass into shape and drying it. D 7

. 12. The method of manufacturing insulating material which consistsin dissolving mineral pitch in a pitch solvent, combining therewith comminuted asbestos in such' proportions that in the completed product tbe pitch will only be sufficient to fill completely the voids, then molding the material 'into shape and drying it. 1 13. The method of manufacturing insulating material which consists in dissolving mineral pitch in benzol, combining therewith comminuted asbestos in such proportions that in the completed product the pitch will only be sulficient to fill completely the voids, then pressing the mass into shape and removing the solvent; 1 7

1-1. The method of manufacturing insulating material which consists in mixing with asbestos a fire, water and acid proof filler, adding abinder consisting of bituminous solvent, in such proportions than in the completed product the binding material will be only suflicient in quantity to fill completely the voids, whereby the resistant properties of the asbestos and the filler are made effective, then pressing the mass into shape and: drying it.

15. The method of making a solid, non-hygroscopic, electrical, insulating composition, consisting in mixing an in- 'organic'fire-pro0f filler with asbestos and a solution of the mixture into the desired form and filling the voids. and then hardening the compressed mass by evaporation of the volatile hydrocarbon, j Y

16. The method 'of making non-hygroscopic, electrical, insulating material consisting-in mixing asbestos with a athe mixture into'desired form'and filling the voids, and then hardening the'compressed mass by evaporation of the volatile-hydrocarbon.

In testimony whereof I hereunto afiix my signature in the presence of two witnesses.

' ROBERT Mijmimn.

Witnesses ABRAHAM Scannsmonn, MATHILDE HELD.

material dissolved at normal temperature in a volatile mineral pitch and volatile hydrocarbon; then. compressing solutionof pitch and pitch'solvent; and then compressing 

